The actress' ad for SodaStream, an Israeli company that does some of its manufacturing in the West Bank, has kicked off a rock 'n' roll battle pitting Israel's rock community against Pink Floyd's Roger Waters.

The ad for SodaStream, whose kitchen appliances turn tap water into seltzer, drew the ire of activists who support a boycott of products made in Israeli-occupied territories.

It prompted Waters to post an open letter to Johansson on Facebook, challenging her decision to endorse an Israeli company and posing a long list of questions about Israel’s treatment of Palestinians.

The post by the Pink Floyd icon was viewed by thousands of members of Israel’s virtual rock community--who might not have rushed to Johansson’s defense if Waters hadn’t mentioned that he had also written Neil Young asking him to observe the boycott.

News of Young’s plans for a concert in Israel this summer has been met with enthusiasm by Israelis, chronically starved for top-tier artists--and also with concerns that he, like others, would come under political pressure to cancel.

Comments ranging from dismay to outrage flooded Waters’ Facebook page, denouncing the mix of music and politics. Some patiently answered Waters’ questions to Johansson. Others sharply told him to stick to music.

One comment came from a radio announcer known as Ben Red, whose show has attracted a Facebook following with tens of thousands of members. “Music is supposed to act as a bridge between cultures and not create a gap between them,” he wrote [link in Hebrew].

Several artists, including Elvis Costello and the Pixies, have canceled concerts over Israel’s politics in recent years.

Others, such as Leonard Cohen and Jethro Tull, reconciled art and conscience with pledges to organizations promoting coexistence and peace.

Despite his support for the Israel boycott, Waters himself performed in Israel several years ago, making his statement by moving the venue from Tel Aviv to Wahat a-Salam/Neve Shalom, a mixed Jewish-Arab community.

Occasionally, political discord roils the local music scene as well.

Recently, Ahinoam Nini, an Israeli performer and outspoken peace advocate, turned down an award from Israel’s composers’ organization, which also planned to honor songwriter Ariel Zilber, who embraced in recent years an ideology of right-wing Jewish extremists.

The rock debate is taking place against a backdrop of sharp words between Israeli officials and U.S. Secretary of State John F. Kerry over the boycott issue.

Nodding to an “increasing de-legitimization campaign” and “talk of boycotts,” Kerry said the stakes for Israel were “enormously high.” Failure could bring an end to Israel’s security and economic prosperity, he insisted.

The comments ruffled Israeli officials, who took Kerry’s comments as a threat.

Attempts to boycott Israel are “immoral and unjust” and won’t achieve their goal, Prime Minister Benjamin Netanyahutold his cabinet Sunday. Furthermore, he said, no pressure would cause him to concede Israel’s vital interests.

Intelligence Minister Yuval Steinitz said Israel could not be expected to negotiate “with a gun to its head” and Economy Minister Naftali Bennett said no nation would “give up its land because of economic threats.”

Such remarks prompted a response from U.S. State Department spokeswoman Jen Psaki, who tweeted Sunday that the secretary has always expected opposition and difficult moments in the peace process, but “expects all parties to accurately portray his record and statements.”